Time resolved thermomagnetic recording process in GdTbFeCo films

The dynamics of domain formation in a GdTbFeCo film during a full cycle of thermomagnetic (TM) recording has been studied by a time-resolved polarized-light microscope. The microscope has 5 ns temporal resolution and sub-μm spatial resolution. Nucleation generally occurs within 15 ns after a write laser pulse. Domain growth and contractive rates are strong functions of irradiated laser power. Domain contractive rates are much higher than growth rates in all cases. The domain growth, shrinkage, and stabilization processes are very reproducible regardless of whether writing is started from nucleation or from a seed domain. A bias field affects dynamic domain size, but not growth rates.